The Washington Nationals are rolling, but Stephen Strasburg is struggling.

Strasburg has allowed 15 runs in 12 innings over his last three starts.

"Yeah, it's frustrating. I'm not pitching to my ability, but I've got to keep grinding," said the right-hander, who has a 6.50 ERA on the season.

"It's definitely something I've never experienced before," he said. "This is a test for me."